At 10am Florida time, SpaceX'sFalcon 9 rocket lifted off, launching the mysterious X-37B spaceplane into orbit. The previous missions relied on United Launch Alliance's Atlas V rockets. This particular vehicle has spent at least 2,000 days in orbit.

The payload's mission is classified, but it's a robotic space plan that looks like a mini space shuttle.

Although the Air Force has stayed mostly silent about the X-37B's details, a little information has trickled out from other sources.

Exactly what the X-37B did during those four missions, or what it will do during the newly launched OTV-5, is a mystery; most X-37B payloads and activities are classified.

On its last mission the "spaceplane" stayed in orbit for nearly two years, but it's unknown how long the current mission is expected to last.

SpaceXhas been valued at $21bn (£16bn), making it one of the most valuable privately owned companies in the world. For comparison, the space shuttles were 122 feet (37 m) long, with 78-foot (24 m) wingspans.

You can watch a livestream of the launch and landing attempt below.

Another Falcon 9 rocket is due for launch October 4 from Vandenberg Air Force Base in California with the third batch of 10 next-generation voice and data relay satellites for Iridium.

According to the forecast by the Patrick #Air Force Base, Irma is expected to reach the area about 900 miles near the launch site during the scheduled take-off.